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The invention relates to an improved elastic element.

Elastic elements are known to be included in shoes or cables in general, e.g. in leashes. One of these is described in the application WO 2007/116272, see herein fig. 1, reference 10, and in particular the leash of Fig. 3 and 4 in WO 2007/116272. It includes a corrugated bellow-portion 14 formed by ridges 18 and valleys 16 located between two flat ends 12. The combination results in a zig-zag structure 20 which can elastically stretch in one direction or axis of elongation X if subjected to a traction force F.

If the elastic element 10 is mounted on a leash it can dump well the tugs of a dog.

However, the problem arises that it is very difficult to calibrate in advance the flexibility and the distension ability of the element 10 without knowing the type of dog tied to the leash. Size and character of every dog requires an element 10 almost made to measure, which is impossible to do practically. Moreover, a user can always use a leash at will, ignoring any suggestion of the manufacturer.

It may then happen that the strength of the dog is excessive, and the elastic element will give way and lose its elasticity, or worse break with dangerous consequences.

The main object of the invention is to solve this problem by improving the state of the art.

The object is achieved by an elastic element having a bellow-folding structure adapted to distend returning elastically along an elongation direction when put in tension, characterized in that it comprises limitation (safety) means connected between the ends of the elastic element and oriented along the elongation direction for determining the maximum extension of the elastic element through their own maximum stretch (of the limitation means).

The limitation means under normal conditions do not intervene, or do so with little effect. But when the elongation of the elastic element exceeds a preset threshold the limitation means (which work in "parallel" to the elastic element) are set in tension and oppose resistance to further stretching of the elastic element. Thus relaxation and/or breakage thereof is prevented. Advantageously, the limiting means comprise a flexible body whose maximum length determines the maximum allowed stretch to the elastic element. Basically a constraint is created for the maximum elongation of the elastic element by setting the maximum possible length of the flexible body. Advantageously the flexible body is provided with adjustment means (e.g. a buckle, a rack connection, Velcro, multi-positional connectors, screws and a plurality of fixing holes) for adjusting its maximum length.

The flexible body may be made of flexible inextensible material, so as to measure precisely the maximum elongation allowed to the elastic element. For example the flexible body may be made of fabric, cord or metallic mesh.

Vice versa the flexible body may be made of stretchable material that opposes a resistance to elongation greater than that of the elastic element. In this case the limit of maximum elongation for the elastic element is defined by the maximum extension of the safety element considering its small elongation as well.

The flexible body may extend externally and next to the elastic element (maximum ease to adjust it or replace it) or be embedded in the material that forms the elastic element (it is better protected).

In the first case the flexible body is preferably sewn or riveted to the ends of the elastic element, while in the second case it preferably comprises a plate or metal or plastic or fabric core that is embedded in the elastic element and reproduces the bellow-profile thereof. These are all simple but effective and reliable solutions.

To enhance the adhesion to the elastic element, especially when it is molded in plastics or rubber, the core has preferably micro-holes.

A connection ring for a snaplink may be attached to the flexible body, whether it is outside or inside the elastic element. This eases the locking/unlocking to the leash. In order to simplify it more, without complicating the structure of the leash and/or the elastic element, the flexible body may be folded on itself to form an eyelet wherein the ring is retained. For superior resistance, it is preferred to insert a ring made of metal or fabric.

The following description of a preferred embodiment of the invention will better clarify the advantages thereof, along with the attached drawings in which:

Figure 1 shows a known elastic element; Figure 2 shows a side view of the elastic element in Fig. 2 with the improvement of the invention;

Figure 3 shows a preferred detail of an elastic element according to the invention;

Figure 4 shows a core of an elastic element according to the invention.

The invention can make use of the elastic element described in WO 2007/116272, and therefore it is also shown in Fig. 2. It is understood that all of the features described for the element 10 in WO 2007/116272 may be integrated in the improved element of the invention.

The element 50 of the invention in Fig. 2 includes the element 10 to which a strap 54, fixed in parallel and next to the element 10, is associated. The inextensible strap 54 is fixed with two rivets 58 to the flat ends 12 of the element 10 and is provided with an adjustable buckle 56 which allows adjusting the length thereof.

In place of rivets 58 e.g. glue or stitching can be used, and the strap 54 may also have a certain minimum elasticity, lower than that of the element 10.

So, when the element 10 is pulled along the axis X (e.g. if it is inserted into a leash), it dilates for some distance, in which it retains spring-back capacity, until the strap 54 tightens, which blocks the extension. In this way the element 10 never goes under excessive traction stress and it is totally avoided that it could damage due to excessive extension. Or in the case of an excessive tug, the element 10 may break and one end of the leash may violently hit the user. With the strap 54 this does not happen, and maximum security is ensured.

At the rivets 58 the strap 54 may be bent upon itself to create a ring or loop portion 60 (Fig. 3) in which to insert a metal or fabric ring 62. To the ring 62 a hook or a leash may be connected, thereby simplifying a lot the connection to and of the element 50.

The accessory element which limits the excursion of the element 10 need not necessarily be external to it. It is possible for instance to embed a metal plate 80 (Fig. 4) in the element 10 itself. If the element 10 is made of rubber or plastic, micro-holes 82 in the plate 80 may favor the mutual adhesion. Or, instead of the plate 80, a cable or a fabric can be used.